Answer: True
Explanation: Ceramics have the property that when the band gap present between the atoms are larger than the light energy then the tend to become opaque because the light scattering is caused . They also show the property of being translucent when there are chances of the light to get a path through the surface of ceramic so they get the light at some parts e.g.porcelain .Therefore the statement given is true that ceramics can be optically opaque or semi-transparent(translucent).
Answer:

Explanation:
Cold water in: 
Hot water in: 

Step 1: Determine the rate of heat transfer in the heat exchanger




Step 2: Determine outlet temperature of hot water



Step 3: Determine the Logarithmic Mean Temperature Difference (LMTD)










Step 4: Determine required surface area of heat exchanger



Step 5: Determine length of heat exchanger



<u>Answer:</u>
<u>of 150 pounds per square inch</u>
Explanation:
Note that the unit for measuring water pressure is called <u> pounds per square inch (psi)</u>
In the case of sprinklers and standpipe systems, a pressure <u>of 150 pounds per square inch</u> was used initially.
Mass affects the weight of an airplane because everything has mass